My little frisk FriskxSans
by Merkaistories18
Summary: Doctor Sans is working with Doctor Gaster and Alphys to find a way to free them all from the underground. The last thing they need is one more human soul when a human does finally fall into the underground San's has his chance, however when it comes to the thing Sans so desperately needs will he choose his heart or his freedom? [FEM FriskxSans] [Scientist Sans AU]
1. Chapter 1

(ó﹏ò｡) wait someone actually wants to read my crappy writing?! WELL Welcome to this story glad you came, hope you enjoy it (◕ᴥ◕).

This story has a slow start but it will take off and it's worth it.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~Something's to consider while reading~~~~~~~~~~~~~~~~~~

Sans is 18

Frisk is 16

This is an AU where Sans is a scientist,

There may be heavy themes in this story such as foul language or depressing themes.

This will be more descriptive and have fewer pictures so if you want a story with lots of pictures this isn't the story for you.

This story will be 3rd person pov most of the time but may switch to character's perspectives so try to keep a close eye on that.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~Thanks for reading~~~~~~~~~~~~~~~~~~

Enjoy this book~

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Chapter 1

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"Sans! That's enough! Step away from the human this has to stop!" Gaster demanded his eyes glowing a dark purple. The two skeletons stood apart as the snow blew feircely around them as if it could read the tension in the air.

Sans glared at the taller skeleton. "No way in hell. I'm sick of this," Gaster growled baring his teeth as his hand rose the gaster blaster with it.

"This is your FINAL warning Sans. I will have the human soul, whether you're on my side or not. Now do the right thing and come back to the lab with me, surrender the human to me! Are you really willing to die for this...this...MONSTER?! Do you want us to be here in this prison that badly!"

"It may be a prison to you, but it's home to me, and this human is no more a monster than you or I."

"Sans. Are you willing to fight your own friend just to spare a human." Blue eyes met purple they glared at each other as the human stood behind Sans shaking.

"Your gonna have a bad time Gaster."

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3 weeks ago

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Another late night in the lab, though Sans enjoyed tinkering around with varies devices and such there was nothing he loved more than being able to go home and see his brother whilst laying on the couch and being oh so lazy.

As he studied the papers infront of him scattered across a messy desk he tapped his chin with his boney finger while humming to himself. Ever since they had been trapped in the underground Sans, Gaster and Alphy's have been trying to find a way to freedom. Well...Gaster and Alphy have, Sans didn't have much of a choice since he was one of the royal scientists that where told to study this by the king.

Sans wasn't very good at building things that's where Gaster came in and Alphy's was always more or so back up which left Sans being the brains of the operation. Right now he was looking over files about human souls and the subject of,

" N. Huh, sounds like a load of crap if you ask me." Sans spoke to himself more so than anything, though he hadn't seen it first hand because he hadn't been born. Gaster had been through all the many humans who fell before and their great power. He remembered him speaking of many monsters being severely harmed until someone like Undyne came along to finally put an end to them.

"All we need it one more human soul." Gaster spoke from behind Sans as he was sorting through some papers himself-a new design for one of his machines it appeared to be. Gaster looked at Sans who seemed to be nodding off, "Would you care for a cup Sans?" Gaster said tilting his head with a warm smile.

It was midnight so it made sense Sans was dozing off, though Sans merely glancing at him grimaced at the cup. "Hell no, get that crap away from me." He complained eyes trailing back to his papers.

"What do you have against coffee Sans." Gaster said crossing his arms looking hurt.

"Ketchup is better." He simply offered as he stood up from the uncomfortable stool he was sitting on.

"I can't see how you could drink that horribly sweet beverage." Sans merely laughed,

"And I can't see how you manage to drink that bitter shit." Sans sighed and pressed his hand against his forehead. "We're not getting anywhere with this Gaster,"

Gaster furrowed his brows and placed the cup down before walking over to the messy desk filled with papers. "Sans, what have you gathered so far?" With a shrug he replied,

"Nothing we don't already know. We need one more human soul if we want to break the barrier, however," Sans paused causing gaster to give him a look.

"What is it Sans." Gaster spoke cariously hoping San's had discovered something though the skeleton shook his head with a sigh, "It's nothing."

"Sans tell me." Gaster demanded. His shoulders tensed and eyes narrowed.

He turned to Gaster his expression troubled, "Here we are waiting for another human to fall down like savage animals. Why do we have to kill them, there just kids. Besides, all those other humans that fell down didn't strike first. At this point where just being murders and that makes us no better than the humans." Sans said with cold eyes.

"Sans," Gaster spoke gently, yet the skeleton continued with hatred filling his white eyes.

"I mean is our freedom really worth the death of these humans?" He persisted getting more upset by the second as he banged his fist against the table.

"Sans." Gaster's tone became more stern as he reached out for San's only to be shoved off roughly.

"Because if we have to kill to be free then how are we any different than the humans." He said louder his eye beginning to flare a bright blue.

"Sans." Gaster grit through his teeth clenching his fist. He'd begun to lose his patience.

"If anything we're just like the-"

"SANS! That's enough." He warned. Sans eye that begun glowing blue died down regretfully and he let out a heavy sigh as he turned away from Gaster. If he had to look at the taller monster for another second he may have swung at him.

He respected Gaster and enjoyed his company, however he didn't agree with his views. Gaster didn't care how many humans died and didn't seem to care if they did die. He didn't see them as another life but just a prize waiting to be claimed, another peace of the puzzle and that pissed Sans off.

Honestly the only reason he hadn't fought Gaster at this point was because he was undre the order of the king to complete this mission to get their freedom back...and he knew it would be pointless to swing at someone who was higher on the food chain than you.

"I understand you don't want to kill, but sometimes we have to."Gaster spoke trying to convince his colluege, though this wasn't the first time they had this conversation and it wouldn't be the last time. San's didn't care for his filisofical bullshit

Sans didn't look at him merely keeping his eyes on the tiled floor of the lab as he clutched in the inside of his lab coat.

"No." He spoke voice deep and serious. "You want to," Gaster didn't respond and Sans pulled his lab coat off putting his blue hoodie on before tossing the lab coat on his chair.

"Where are you going." Gaster demanded as Sans begun walking out.

"Home, I'm tired." Sans waved though he wasn't smiling, he never seemed to when he was in the lab there where rare times when he did and those where before they where ordered to find a way to free them from the underground. He ignored the call of his name behind him and with the snap of his fingers he was gone.

He turned the knob and walked in almost immediately being greeted by the smell of spaghetti that he was so familiar with. Once the door closed he heard the loud voice that he adored so much from the kitchen,

"SANS! BROTHER YOU ARE HOME HOW WAS POTROL BROTHER?!" Pupyrus said running over and giving Sans a tight hug before putting him down. Once he put him down he noticed the expression on his brothers face, the usual smile absent as his white pupils stared vacantly into the carpet.

"BROTHER? WHAT IS WRONG?" Papyrus asked nudging his brother who's head shot up seeming to come out of his thoughts.

"Huh-oh don't worry bro I'm just chilled to the bone." Papyrus gave Sans a look but instead of scolding him for the bad pun he let it go which only threw Sans off evermore.

"IF YOU SAY SO...COME BROTHER I WILL SERVER YOU MY SPECIAL SPAGHETTI. THEN YOU CAN TELL ME HOW YOUR PROTROL WENT." Sans shrugged and fell onto the couch trying to smile the best he could even though he really wasn't feeling it. He hated lying to his brother but it was better Paps didn't know the things he had to do in that damn lab. He'd rather his brother think he was mindlessly walking around looking for humans like him...But he didn't want his brother to worry for him, he never did. He may be trapped in the underground but he'd come to like it and think of it as his home...he was contempt with everything here and that was fine for him.

Though everyone wasn't like that and they just had to be free...and freedom didn't come well...free...blood had to be spilled weather it was there blood or someone else blood.

Sans sighed clutching his bony hand into a fist and sighing. He just wished it didn't have to be that way, he didn't like the humans but they never personally hurt him or his brother so he had no intent to kill them and the children that fell down here had no part in that war they where just that, children who fell down here only to be mercilessly killed.

He rubbed his temples and leaned back into the couch closing his eyes allowing the sound of his brothers humming to be the last thing he heard as he drifted off to sleep.

Sans normally awoke sometime in the afternoon and it was with his brother yelling at him to get up, though today was different.

Instead of being awoken by his brothers loud yelling demanding he get out of bed instead he awoke to the sound of his phone ringing. He wairly opened his eyes just a small bit enough to barely see the phone vibrating on his end table. He groaned and ignored it turning over on his side to face the wall hoping that would help.

However only a few momments later the phone rang once more. With a groan Sans opened his eyes and with a heavy sigh managed to grab the phone off his nightstand without sitting up. He looked at the caller and to his surprise it was Gaster. Normally if he wanted something he'd have Alphy's call him instead because he was always to busy to pick up the phone.

Reluctantly he answered the phone and waited to hear Gaster tell him about how he propably made some new kind of discovery and for Sans to tell him he really didn't care. Though as he answered,

"Sans!" He winced away from the phone,

"Ah-geez Gaster did you call blow my ears off." Even though he didn't have any ears. Though Gaster ignored him and Sans could hear him shuffling around in the backround which wasn't too abnormal for him but he got a bad feeling from it.

"Sans I need you to come down to the lab right away!" He yelled and Sans decided it be best to keep the phone a safe distance from his head from now on if he didn't want to go deaf that is.

"What for this time, seriously Gaster it's," He paused glancing at his clock, "2:00 in the morning!" Gaster groaned on the other side of the line. Sans didn't care what he had to say, nothing he said could get him out of bed right now and surely not at 2 in the damn morning!

"Sans this is urgent. Alphy's said she saw a human on one of her camera's by the large door to the ruins!" That caught his attention. He sat up suddenly the phone to his none existent ear.

"Are you sure it wasn't a squiral or something?" Though his words where humerous his tone was anything but that.

"I'm being serious Sans. She showed me the footage and it is indeed a human!" I sighed,

"Uh-ok ok, I'll be right over." Sans hung up the phone after that and simply sat there on his bed for a bit just...thinking.

A human finally fell into the underground...he clsoed his eyes and sighed visions of their king killing the other kids flashed before his mind, blood, children's bodies, and monsters cheering as if it where some action movie...

It all made Sans stomach (if he had one) twist and turn making him want to hurl. It was sickening how the other monsters loved to see that...Sans didn't understand it and Papyrus had never seen a human being killed infront of his eyes only heard about it so it couldn't be helped. When he'd heard about it he only questioned Sans why the monsters and humans couldn't be friends. That's why he loved his brother so much, so innocent unlike the rest of the underground. Hell, even the kids wanted to see the humans die thanks to people like Undnye,

Sans opened his eyes and urged himself to get up, once he did he pulled on his slippers and blue coat.

He trudged out of his room and barely made his way down the stairs, as he was on the stairs he glanced back at his brothers room and sighed once more. "I'll be back soon bro."

He grabbed some ketchup from the fridge before teleporting to the lab because it was way to far away to walk, and he was way to lazy for that.


	2. Chapter 2

Chapter 2

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"Sans, I'm glad you're finally here. " Gaster greeted Sans with a tired smile. Meanwhile, the skeleton replied with a grunt as he pulled his coat off not even bothering with the lab coat as he took a swig of the ketchup bottle.

"Please don't drink that in my presence." Gaster requested as he grimaced at the beverage.

Taking another swig Sans replied rudely "You called me here this early, you ant in any position to be making demands." his brows furrowed as he wiped some ketchup off his mouth, "Anyway, where is this human footage?" He asked as he placed the bottle down on the table.

Gaster only gave Sans a brief glare for his rudeness before turning to the large screen and stepping up to the control pad. He pressed a button and a picture came onto the screen.

Sans chocked as he saw the figure and it was undoubtedly a human.

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**_*You leave the ruins. It's cold here and it feels...weird._**

The snow crunched under my feet as I walked, it's colder here so I'm glad I have the sweater even if it is a little torn from the fall. As I exit the ruins the door closed with a loud creak which puts me on edge. I hope nobody...or anything heard that...the last thing I want it to have to fight something. I don't think I'd win that fight anyway, I notice something peeking out from the bushes...gradually I walk closer to it...heart racing in my chest...

I realize that...it's...a camera?

I feel uneasy that I'm being watched but try not to let it show, I turn to the camera and crouch down so I'm at eye level with it, I look at it curiously before offering a kind smile to whoever is watching hoping they're friendly and a short wave before standing up and turning away.

The fact that I fell down doesn't bother me because I did that on purpose. I know what you're thinking, I should be worried about getting to the surface but honestly, I'm not...Why would I want to go back up there...I don't have any parents, I'm an orphan who isn't treated to kindly because of my over baring kindness...despite being beaten up I never hit back...I have no friends, no family and the orphanage is miserable for me.

I hate my life, I see no point for it so...I decided to try and end it when I jumped down the mountain, though I obviously failed and wasn't even harmed my sweater is a different story though...

I don't really know what to do now. I don't know if I should try again down here or just explore maybe...as I walk the cuts under my sweater begin to burn once more as I grip them and wince reminding me of the bad memories I keep trying to push away...to forget...

Ouch...ugh it stings, but not as much as it first did...I-I've gotten used to pain...you could say..

I shook it off ignoring it and continued on until I saw what looked like a bridge and...is that supposed to be a gate? It's far to big to stop anyone, I walked forward stepping over what looked like a heavy trunk of a tree and proceeded near the bridge. I suddenly froze as I heard the sound of footsteps behind me,

My head whipped around...

but nobody was there...I took a deep breath...it's okay Frisk your just imagining things that's all...I moved forward until I was at the entrance of the bridge,

S N A P

My heart skipped a beat and I turned around so fast I almost fell, the branch...

was destoryed...

*You are filled with fear

My face grew pale and my blood ran cold...I did not imagine that...someone is following me..._something_...is following me. I turned my back to the bridge eyeing the spot where the trunk had been broke, I moved back away from the spot I saw not wanting to take my eyes off it...if someone was following me I was going to catch them this time...but before that chance came...

My boot slipped on something and I began to fall back as the wind rushed past my ears and the cold prickled my face like needles. I looked over my shoulder seeing the ground coming closer and closer I was falling into the gap between the bridge...crap...

well...I wanted to die...though I wish I could have explored this place a litte more. I just sighed and closed my eyes feeling my chest tighten and my hands run cold,

I nearly waited for death to come not bothering to scream as I felt the wind rushing past my ears. Though suddenly it all stopped...the wind in my ears...the cold brushing past my face the racing of my heart...and I thought I was dead but I felt no pain...just...a warm sensation...

I opened my eyes gradually and looked at my hands...I was engulfed in a blue aura. I looked behind me the ground just mere inches away from me and I was slowly being pulled up as the ground of the ravine got further away... but...I realized I was floating...wait...

FLOATING?! Why am I floating!?

Then I saw it, my soul was not red...but blue. I was being pulled out of the ravine by...something...and with a soft thump, I landed in the snow face first...that hurt...The warm sensation I felt was no longer there and my soul had returned to it's red color...

I was cold again...I pushed myself off the ground with a soft grunt and wiped the snow off my face.

"Hey kid, that was close huh?" I heard a deep voice above me though it sounded...friendly...

Still on my knees I sat there shivering the snow had soaked through my jeans where my knees where. I looked up coming face to face with...a...

Sk-sk-skeleton!? My heart raced, though the line that would be his lips formed into a gentle smile. "Hey buddy relaxes, it's okay I won't hurt 'cha." I tried to relax and he extended his boney hand, I shied away from his hand a bit. I looked at it looking at all the bones and then at my own hand...

I hesitated but gradually moved my hand to his and wrapped my fingers around the bones that made up his hand...it felt...weird but...warm once more...with a soft tug me pulled me off the snow,

Out of all the things that I expected to happen...this was not one of them.

So this is the human? Being this close to them I could get a better look at them now, they were taller than I thought just about my height if not an inch shorter. Their brown hair was messy and rested on their shoulders, their brown eyes avoided me filled with anxiety and fear as they stared at the snow. Their sweater was ripped and torn on the arms and stomach area and the jeans they wore were now soaked at the knees. Most likely from falling in the snow; Their face was pale compared to the rest of their body, they must be scared.

I realized I'd been holding their hand longer than necessary and awkwardly pulled it away reminiscing at the touch of their cold skin. I looked at them, they didn't seem dangerous they just seemed scared like any other kid that fell down here though they were obviously older than those children; In their early teens, I would say?

"Sorry didn't mean to _snow_ you down." Their eyes looked in my direction, the brown hues sparkled surprised and a small smile found it's way to their lips. I found myself smiling as the human began to laugh.

"W-was that a pun?" They asked nervously, their voice is higher-pitched than my own. I shrugged,

"Yeah, I got a _skele-ton_ of them." I gave them a wink and they laughed again their cheeks reddened. There we go, they seemed to be more at ease, let's try this again.

I extended my hand and with my usual grin I said in a relaxed tone, "I'm San's, sans the skeleton." They looked at my hand again observing it. I noticed they seem to have issues with trusting people, I suppose I'll have to report that to Gaster later. After all, I'm only here because he wants me to report the human's behavior even though I don't agree with him it's my job. I don't have a choice in the matter.

They finally take my hand in theirs and offer a smile but its nervous. "M-my name is Frisk...I'm sorry I-I've just never seen a skeleton." As I took my hand away I replied,

"I understand it must really rattle your bones." They laughed again their laugh was actually kind of cute. It reminded me of Pap's laugh, so pure and innocent and not forced in the slightest. The same went with their expression though they seemed afraid of interacting with anyone. I wonder why that is, many of the other humans who fell down here had no problem but this one...is...different.

"Thanks for...saving me but...you didn't have to." That was a weird sentence, I raised my brow wanting to address that but I didn't want to sway their behavior so I just simply swayed my hand,

"Eh it's no trouble you just gotta...blue...more careful." This time they didn't laugh, I guess that one was kinda bad, they only offered a small smile.

"Hey kiddo listen, you look cold, how about I take you to snowdin to warm up?" Again they seemed to shy away from the offer putting their hands up.

"N-No it's okay..I-I'll be fine." I furrowed my brows I wanted to make them but...

I sighed and shrugged, "Alright. Well kid if you need me just call for me and I'll be there to help ya."

Why did I say that last part? It's not part of my job to help them...

Despite that, they seemed to smile and with a nod they walked over the bridge and out of my view...I stood there for a bit considering what just happened...

Suddenly my phone buzzed, again...seriously? When can I get a break around here...

I sighed answering it.

"Yeah," I said more annoyed than anything.

"G-g-g-gaster w-w-wants y-y-you to c-c-come b-back to that l-lab." It was alphy's, hadn't heard from her in a while. Thought I was annoyed I didn't take it out on her.

"Alright, I'll be there shortly," I spoke before hanging up.

This...is going to be a loooong day.

Their skin was a light tan, hair a chestnut brown and they looked at the camera their eyes closed though it seemed like they could still see perfectly fine. They wore a colorful purple and pink striped sweater and blue jeans with a pair of black shoes.

"I-it really is a human," Sans said taken aback, blinking at the large screen as if to confirm what he was seeing was real.

"Of course it is. Would I lie to you about such an important topic." Gaster grumbled pausing the footage. Sans notice the snow and trees around them.

"So a human fell down into the underground. What do you want me for? What to document the gruesome way they die?" Gaster gave Sans a look.

"Sans, I know you don't agree with this but don't you see with this last human soul we could be free we could-"

Sans put a hand up glaring at Gaster stopping him from continuing that sentence. "You're right, I don't agree." Sans turned his back to Gaster.

_But I don't have a choice..._

He thought to himself as he pulled his coat back on.

"So what do you want me to do, because I know you didn't just call me here to tell me the news," Sans spoke taking a drink from his ketchup once more because it was the only thing that could calm him down.

Gaster rolled his eyes walking behind Sans, "Oh don't say it as if it's a bad thing." The taller skeleton complained his arms outstretched, though Sans merely ignored his remark. Gaster stared at his colleague for a bit before giving up and allowing his arms to fall to their sides. "I need you to keep an eye on this human." He finally says in a less than joyful tone.

Sans chocked on the ketchup. "W-WHAT?!" He said head whipping around his eye flaring a bright blue. "Why me of all people, why can't you get Alphy's to do it?" It was bad enough he had to help kill these humans but he was NOT and he meant NOT going to babysit one while he waited for them to be killed.

Gaster shook his head waving his hand around dismissively as he walked to his desk, "Alphy's is to..." He paused looking for the right words as to not speak rudely of her. "...Clumsy, she would easily be discovered by the human and I need to know the human's behavior for my research without them being known they are tracked." He turned to Sans with a hopeful look in his eyes. "You Sans are fairly quiet and your teleporting skills can be helpful." Sans rolled his eyes,

He didn't want to do this but he didn't have a choice. "What's the REAL reason you want me to follow them around? Because I don't recall you mentioning King Asgore or even Undnye knowing about this human, it's strange you haven't informed them the second you saw the footage." Gaster looked at Sans for a moment staring blankly at him before bursting into laughter,

Sans wasn't amused though. He merely just continued to stare at Gaster annoyed waiting for a response.

"Hahaha-Alright Sans you've caught me." Gaster proudly walked over to the board hanging on the wall. He pulled the blue tarp off the board to reveal designs for what looked like one of Sans's gaster heads but much larger and tubes sticking out from it...Seeing this made San's stiffen and chills ran down his spine. He didn't know what it was but...something about that design felt...erie.

And...

Dangerous...

Sans just stood there frozen as his eyes were glued to the plans for what looked like a living monster, meanwhile, Gaster hadn't even noticed that. He had a huge grin on his face and his expression was lit up with joy and excitement. He looked like a proud kid revealing something they'd been working on but didn't know it was wrong.

"You see Sans this machine that I've been working on for years is called the DETERMINATION EXTRACTOR. Once we kill the human it will extract their determination and not only will we be able to break through the barrier but will be stronger than even full-grown humans."

Sweat dripped down Sans's face as he stared at Gaster frowning. "Gaster...what exactly are you planning.." Sans spoke feeling uneasy. He wanted to say more but something told him it was best to remain quiet.

It was then Gaster turned to face Sans and his soul fell like a stone seeing those purple eyes wide open and lit up and that crazed smile on his face...He'd never seen that look before...never in his entire life...It was just...wrong...it wasn't right at all...

"Sans when we achieve freedom...I intend to keep it and I won't let those filthy humans take it away from us again..." His voice was quiet...tone sinister and dark...something in him had changed...and Sans didn't like it one bit. "When we reach the surface..."

His eyes grew wider as if they would pop out of their sockets and his smile grew wider as he began laughing, "I'll wipe out every human up there with the power of DETERMINATION!" Sans backed up a bit from Gaster. "And once I find a suitable monster to inject the DETERMINATION into they will be a killing machine to powerful for any human to survive!" His laughter grew louder and more rambunctious

"Gaster..." Sans said quietly but the laughter continued sounding crazed and mad...Sans furrowed his brows. "GASTER!" He yelled slapping the taller skeleton. Gaster blinked seeming to have come back to his senses...

"Ah-I-I'm sorry Sans what was I saying?" Sans gave him a look and just shook his head.

"Nothing-look I'm gonna head out and search for that human," Sans replied, before Gaster could get a word out Sans had already teleported away.

He didn't know what was going on with Gaster but whatvever it was he knew it wasn't good. 


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